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Comparison of cell survival models for mixed LET radiation
N Tilly1, A Brahme, J Carlsson
1Department of Medical Radiation Physics, Karolinska Institutet and Stockholm University, Sweden.
Purpose:
Biophysical models for predicting survival for mixed LET radiations have been investigated by comparisons with experimental results from heavy ion irradiations. The aim was to choose a model for further theoretical studies on the effects of a variable RBE for protons.
Methods And Materials:
Predicted survival curves by the Katz track-structure model, the linear quadratic model, LQ model, by Kellerer and Rossi and the lesion additivity model of Lam were compared to experimental survival curves for V79 cells that were irradiated with a mixture of nitrogen ions with an LET of either 78 or 165 keV/microm and 60Co gamma-rays.
Results:
Results showed that all three models could predict survival within the uncertainty of the measurements for the different mixed radiation schedules used in this study.
Conclusion:
The choice of model could be made on other grounds, such as the type of model parameters and the availability of biological data for these parameters. Also, the possibility of including dose-rate effects and repair functions should be considered. For the purpose of carrying out theoretical studies on the effects of a variable RBE for protons, the LQ model was preferred.